I find a number of people that they find it difficult to speak to anyone at any place the following can be some reasons

Not feeling confident of themselves

Fear of making a mistake

Fear of others mood

Not having the right content to speak

But, the fact is nobody is ever interested what you speak and how you speak unless it hurts their feelings or it is a matter sarcasm.Now to tackle this problem of fear to talk one can follow the following tips.

Always have some knowledge relavant to the person you are speaking to. Whether it is your CEO also you dont have to worry if you have a proper reason to speak

Always have funny content in your mind like jokes. just relate any joke with the current context.

do not criticize or comment at others.

Try to develop a friendly nature with who ever you speak. specially, if he is your colleague sitting next to you.

Remember, be patient to listen to others, and encourage others to speak about themselves and trying to beat your trumpets all the time.

And finally try to have a positive set of mind, and have some motivational stories with you, people listen to such stories interestingly whether they follow or not.

You can also equip yourself with some thriller and horror stories which can be a useful entertainment when sitting in a group.

You can always go through some self motivation websites so that you can develop some positive attitude and some motivational quotations which gives some weight to your personality.